*{
    margin:0;
    padding:0;
}
ul,li{list-style:none;}

.div1{
    width:328px;
    margin:20px auto; }
.a li{ 
    float:left;
    padding:15px 20px ;
    background-color:#ccc;
    cursor:pointer;
}
.a li:hover{
    background-color:#666;
    color:#fff;
}
.a:after{
    content:"";
    display:block;
    clear:both;
}